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(No Model.)

J. B. HURD. TELEGRAPH APPARATUS FOR BRANCH OFFIGBS.

No. 469,856. Patented Mar. 1, 1892.

Swim um wi/lmwm WM 3 M Iii/M4 UNITED STATES PATENT OFFICE.

JOHN B. I-IURD, OF RED BANK, NEYV JERSEY, ASSIGNOR TO THE WESTERN UNION TELEGRAPH COMPANY, OF NEW YORK, N. Y.

TELEGRAPH APPARATUS FOR BRANCH OFFICES.

SPECIFICATION forming part of Letters Patent No. 469,856, dated March 1, 1892. Application filed March '7, 1890. Serial No, 343,027. (No model.)

To all whom it mayconoern:

Be it known that 1, JOHN B. HURD, a citizen of theUnited Statesof America, residing at Red Bank, Monmouth county, New Jersey, have made a new and useful Improvement in Branch-Office Telegraph Apparatus, of which the following is a specification.

In large cities it is now common to connect main telegraph-lines at a central station with branches or loops connecting the main line with local stations oftentimes several miles distant.

The object of my invention is to so connect local stations with the main line at a central office that a local operator may have the means of communicating with the central office to inform the latter of line trouble, which he may detect in the course of transmitting or receiving signals. The necessity for such an arrangement arises from the fact that the local operator has ample means of detecting line trouble; but he isunprovided with apparatus for communicating with distant points on theline or for making tests to locate and correct the trouble, or for connecting his loop and office with another line if incapacitated for service. This Work must be done at the switch-board of the central office. To this end I employ at the central oflice a low-resistance magnet for operating a relay, gong, or other sounding device which remains unaffected by telegraphic signals, while at the local station an earth branch and key are connected to the loop. Upon depressing the key a circuit is formedfrom the central station through the main battery, the low-resistance magnet, a portion of the loop, thekey branch at the local station, and the earth return. By this means the main-line battery is provided with a short circuit by the depression of the key, and sufficient current will flow through the low-resistance relay to cause signals to be given, thus announcing to the central oflice that there is difficulty on the line requiring correction.

In the accompanying drawings, L is the main line, whose circuit is normally closed to earth through the spring-jack m a, low-resistance magnet R, and battery M B. A local station A is joined with the line by means of a loop Z and a switch-plug P, whose tip is formed of two metallic portions 0 p, separated by a sheet of insulating material. hen the plug is inserted, the jaws of the spring-jack m n are separated and joined, respectively, with 0 19. With this arrangement a circuit of low-resistance is formed from the main office to the local station upon the depression of the key K through the main battery M B, magnet R,aportion of loop Z, and the earth from E to E. If the operator at A finds that the line is not in satisfactory condition, he may depress key K, thereby calling the attention of the operator at the central station by relay R, who thereupon, with almost no loss of time, will proceed to locate and correct the difliculty, or, if

need be, give local station A connection with another circuit.

I am aware of the patent of M. G. Kellogg, No. 386,886, dated July 31, 1888.

That I claim, and desire to secure by Letters Patent, is-

1. A main telegraph-line extending through a central station to an outlying local station and thence back to the central station, an indicating-magnet which is irresponsive to telegraph-signals and a battery, both placed in said main line atthecentral station, an earth branch connecting said loop with the earth at thelocal station, and a key placed in said earth branclrfor enabling the local operator to signal the central station while he is at the same time in communication with a distant mainline station, as and for the purpose set forth. 8 5

2. A main telegraph line L, extending through a central station to an outlying local station A and back to the central station, an indicating magnet R, irresponsive to telegraph signals from a distant station, and a battery M B, both placed in said main line, an earth branch connecting said loop at the local station with the earth, and a key placed in said earth branch for the purpose of enabling the local operator to signal the central 5 station without interfering with telegraphic transmission from the distant station.

3. A main telegraph-line L, extending from a distant station to a central station and K, placed in said earth branch, and aspringthence to an outlying local station, an indijack at the central station, as and for the purcating-magnet which is irresponsive to telepose set forth.

graph-signals from the distant station, and a JOHN B. IIURD. battery M B, both placed in said main line, a Witnesses: normally-open earth branch connecting said JOHN C. SANDERS.

loop at the local station with the earth, a key EDWIN F. HOWELL. 

